“Just like light waves moving through a lens, sound waves curve and bend as they move through the ocean, and they also reflect off the seafloor and sea surface.” “We then used seafloor acoustic models and oceanographic data to determine how the sound changed as it moved through the environment.” “The surround sound recordings allowed us to calculate the precise location of the whales,” Dr Miller said.
Some 1915 calls, across 205 hours of recordings, in waters deeper than 1000 metres, were then assessed for their source level. While the instruments detected whale calls from hundreds of kilometres away, only calls less than 50 kilometres away were used in the study. The calls were detected using passive acoustic instruments known as sonobuoys, during a voyage off Antarctica in 2019.Īrrays of two or three sonobuoys were deployed into the ocean, up to 40 kilometres apart, to capture “surround sound” recordings, and enable triangulation of the whales’ locations. “Understanding the power of their calls will also help us understand the whales’ natural communication space, and how their communication with each other might be affected by human-made noise.” “Being able to listen for these animals gives us a powerful tool to detect when and where they occur and to monitor change over time, and in the future it may allow us to estimate how many whales there are.” “Blue and fin whales were hunted to the brink of extinction and remain extremely rare, even today, so they are very hard to find by visual observation alone,” lead author Dr Miller said. While the so-called ‘D-calls’ of blue whales and ’40 Hz’ calls of fin whales have been recorded around the world for decades, a study published in Frontiers in Marine Science gives the first estimates of the power or ‘source level’ of five different types of blue and fin whale calls in the southern hemisphere. “If you’ve ever been in traffic next to someone with a very loud sound system, that’s what the vibrations would feel like – you’d be feeling the bass.” “However, if you were in the water next to a singing whale you would likely feel the sounds as vibrations,” Dr Miller said. RSV Nuyina – Australia’s Antarctic icebreaker.Classification of scientific publications.Nuyina icebreaker construction timelapse.Message for family and friends of expeditioners.What happens before departure & on arrival at station.Frequently asked questions for scientists.2022 Changes to the Australian Antarctic Science Program (AASP).Environmental remediation & restoration.History of Australian Antarctic stations.
Convention on the Conservation of Antarctic Marine Living Resources.Australia and the Antarctic Treaty System.Environmental Impact Assessment approvals.
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